With a proposed payout of more than $1 billion, one major chapter of a nearly four-year legal saga that left Toyota Motor Corp. fighting hundreds of lawsuits and struggling with a tarnished image has ended, though another remains.

The Obama administration is preparing to warn car owners whose air bags have been replaced in the past three years that dangerous counterfeit bags may have been installed, according to auto industry officials who have been briefed by the government.

A government investigation now includes 600,000 Toyota Camrys along with other vehicles after wide reports of fires in the power window switches. The investigation has now been expanded to over 1.4 million cars and SUVs.